In U.S. Pat. Nos. 3,347,454; 3,672,564; and 3,719,406, centrifuges are disclosed utilizing collapsible centrifuge bags for the continuous washing of blood cells positioned in the bags during the centrifuge operation. To provide a continuous connection with the exterior while the centrifuge is rotating, a rotary seal distributor member is disclosed including an apertured spindle coaxially mounted in a housing and projecting from its end, with several spaced ring seals positioned about the spindle. The annular spaces which are defined by the ring seals serve as separate chambers through which fluid flows either into or out of the system. For example, two separate washing systems may be routed through the same rotary seal structure, as illustrated in the last-cited patent.
The rotary distribution seal of the prior art has occasionally encountered some functional disadvantages. For example, when a substantial pressure differential exists between solution passing into the system through the rotary distributor member, as compared with wash solution passing out of the system through the same distributor member, a pressure differential exists between different annular chambers separated by the ring seals. This can result in leakage between the respective chambers, which is distinctly undesirable, particularly when two different types of blood are being simultaneously washed in a centrifuge system.
Also, difficulties have been encountered in the assembly of the flow tubes in the spindle of the rotary seal member to provide reliable leak-proof operation.
In accordance with this invention, an improved rotary seal member is provided in which leakage problems encountered by previous rotary seal members have been eliminated, while still providing a structure having great ease of assembly and reliable operation.